Apr 29th 2025
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Hubble at 35
On April 24, 2025, the Hubble Space Telescope quietly celebrated its 35th anniversary in orbit. Far from being an outdated relic, this incredible observatory continues to produce groundbreaking science and breathtaking images of our universe. In a recent episode of This Week in Space, hosts Rod Pyle and Tariq Malik welcomed Dr. John Grunsfeld—former NASA astronaut, former NASA Chief Scientist, and self-described "Hubble Hugger"—to discuss the telescope's past achievements, current status, and uncertain future amid proposed NASA budget cuts.
The Hubble Hugger
Few people have a more intimate relationship with the Hubble Space Telescope than John Grunsfeld. As an astronaut who performed a remarkable 58+ hours of spacewalks across three Hubble servicing missions, Grunsfeld earned his nickname "the Hubble Hugger" through his hands-on work with the telescope.
"When people ask, when did you start training to repair the Hubble Space Telescope, my pithy answer is at birth," Grunsfeld joked during the interview.
Grunsfeld's journey to becoming one of Hubble's most important caretakers began with his lifelong passion for science and space. Born in 1958 (a "baby of NASA," as he describes himself), Grunsfeld was inspired by the early space program and a third-grade assignment on physicist Enrico Fermi. His path led him from studying physics at Caltech to becoming an astronaut in 1992—just two years after Hubble's launch.
Hubble's Scientific Legacy
While the stunning images produced by Hubble have captivated the public imagination for decades, Grunsfeld emphasized the telescope's profound scientific contributions.
"Hubble was designed originally for a 15-year lifetime," Grunsfeld explained. "Its sort of high-level requirement was to measure the expansion of the universe, in order to get an age estimate of how long our universe has been around since the Big Bang."
This mission was accomplished spectacularly. Not only did Hubble help determine that the universe is approximately 13.8 billion years old, but it also led to one of the most significant cosmological discoveries of our time: the accelerating expansion of the universe driven by dark energy.
"Adam Reese at Johns Hopkins University and Space Telescope Science Institute was making those measurements and in his notebook found that the universe looked like it was accelerating," Grunsfeld recounted. This unexpected finding eventually led to the 2011 Nobel Prize in Physics for Reese and his colleagues.
Grunsfeld noted proudly that Reese has acknowledged the critical role of Hubble servicing missions in this discovery: "No Hubble servicing, no Nobel."
The Engineering Marvel of Serviceability
What sets Hubble apart from most space telescopes—including its successor, the James Webb Space Telescope—is its serviceability. Designed to be regularly updated and repaired by astronauts, Hubble has undergone five major servicing missions that have kept it at the cutting edge of astronomical technology.
"The brilliance of Hubble is that it was designed to be serviceable, almost everything," Grunsfeld explained. This design philosophy has allowed NASA to replace outdated instruments with state-of-the-art technology multiple times over the telescope's lifetime.
Grunsfeld shared fascinating details about the physical challenges and ingenious solutions involved in these repair missions. From developing specialized tools to working with tiny "sub-miniature assembly connectors" in bulky spacesuits, the astronauts who serviced Hubble overcame remarkable obstacles.
"There were times where I sort of marveled... I thought I feel like I'm in shirt sleeves, I'm doing this and it's so familiar that I forgot that I was in a spacesuit," Grunsfeld recalled of his work on the telescope.
Hubble's Uncertain Future
Despite its continued scientific productivity, Hubble faces an uncertain future due to proposed cuts to NASA's science budget. Grunsfeld expressed deep concern about reports suggesting NASA has been directed to begin shutting down Hubble operations.
"My understanding is that NASA has been directed already to start turning off instruments and laying off the engineers and scientists who support Hubble in order to save a few tens of millions of dollars," Grunsfeld said. "And that's just crazy."
The proposed 50% reduction to NASA's science budget would affect not only Hubble but also potentially the James Webb Space Telescope and the nearly-complete Nancy Grace Roman Space Telescope.
Grunsfeld didn't mince words about these proposed cuts: "I think it's nearly insane to cut the NASA science budget because, one, Americans love NASA science and they're the taxpayers they are paying taxes to get a return."
He pointed out that NASA science missions generate significant returns on investment—with estimates suggesting every dollar invested in NASA generates seven to nine dollars in GDP—and are crucial to maintaining America's scientific leadership internationally.
The Next Generation: Looking Beyond Hubble
Despite current budget concerns, plans are already underway for Hubble's successor. Grunsfeld discussed the Habitable Worlds Observatory, a proposed "super Hubble" specifically designed to search for signs of life on planets around other stars.
"The current thinking is it will be about a six-meter mirror. Hubble's is 2.4 meters," Grunsfeld explained. Unlike Hubble, this new observatory would be positioned a million miles from Earth, making human servicing missions impractical.
Instead, Grunsfeld envisions a future where robotic servicing missions would maintain and upgrade the observatory. "By 2045, say, we should have very capable servicing robots that we can hire as a commercial service to deliver the instrument, swap them out and then send the observatory back on its way," he said.
His mantra for designing this next-generation telescope: "Make it so easy, even a robot can do it."
A Call to Action
Throughout the interview, Grunsfeld emphasized that citizens can influence these budget decisions by contacting their representatives in Congress.
"Write your Congress folks, write your House of Representatives representative, write the Senate... every American citizen can give President Trump their input," Grunsfeld urged. "If they don't hear from you, they don't know and they make decisions based on what their constituents, people like you, tell them is important."
The Legacy Continues
As Hubble passes its 35th anniversary, its scientific legacy remains unmatched. Barring any major failures, Grunsfeld believes Hubble could continue producing groundbreaking science for another decade.
If it reaches that milestone, Hubble will have served humanity for 45 years—an extraordinary achievement for a mission originally designed to last just 15 years. This longevity is a testament not only to the telescope's robust design but also to the vision of making it serviceable and the dedication of the astronauts, engineers, and scientists who have kept it operational.
For the full conversation with Dr. John Grunsfeld, including his personal journey to becoming an astronaut and more details about Hubble's scientific discoveries, tune in to Episode 158 of This Week in Space.
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